Synsacra and pelves (in B, D–F) in ventral view. A Spheniscus magellanicus (MLP-ORN 1598); B Pygoscelis adeliae (MACN-Or 68557); C Aptenodytes forsteri (MLP-ORN 15192); D Pygoscelis papua (MLP-ORN 783); E Pygoscelis antarcticus (MLP-ORN 1138); F Eudyptes chrysocome (MLP-ORN 1596). Synsacral segments: TS – Thoracal Segment; TLS – Thoracolumbar Segment; LS – Lumbar Segment; SS – Sacral Segment; CS – Caudal Segment. Abbreviations: api – ala praeacetabularis ilii; pc – processus costalis; pt – processus transversus; T – thoracic vertebra. Black circles indicate each individual vertebra. Scale bar: 10 mm.